Cape Town's first winter storm hit the city early on Saturday morning, said disaster management.

"The rain hit shortly after 7am this morning," said spokesperson Greg Pillay.

"We have had reports of widespread flooding on a number of roads in the city as well as six informal settlements," he said, but added that the extent of the damage was still being evaluated.

In an advisory on Friday, the South African Weather Service warned that the south western peninsula and areas near Table Mountain would be particularly affected by the heavy rainfall.

"The Western Cape is already experiencing rain and gale force winds along the south western coastline," weather forecaster Luis Fernandes said on Saturday.

"The cold front will move along to the Eastern Cape and although they will not experience the same heavy rainfall, there will be gale force winds along the coastal areas, such as Port Elizabeth and Cape St Francis," he said.